Printing device and method for controlling printing device

ABSTRACT

The advantage of the invention is to prevent the efficiency of printing from being deteriorated due to execution of an authentication process during a print process by arranging an authentication process not to be conducted during a print process. The multi-purpose device is connected to the authentication switch through the LAN. The authentication switch conducts an authentication process of a device connected to the LAN, and disconnects a connection between the device and the network in a case where the device cannot be authenticated. The multi-purpose device has the authentication requesting section that requests the authentication process with respect to the authentication switch; and the printing mechanism that prints print data. In a case where the printing mechanism conducts the print process, the authentication requesting section requests the authentication process before the printing mechanism starts the print process.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to Japanese Patent Application No.2012-122791 filed on May 30, 2012. The entire disclosure of JapanesePatent Application No. 2012-122791 is hereby incorporated herein byreference.

BACKGROUND

1. Technical Field

The present invention relates to a printing device, a printing system,and a method for controlling the printing device, in which communicationis conducted by connecting to a network.

2. Background Technology

In a communication device that conducts communication by connecting to anetwork, an authentication process is needed for connecting to anetwork. As a standard for this authentication process, the IEEE802.1Xstandard described, for example, in Patent Document 1 is known.According to the IEEE802.1X standard, a communication device conductstwo-way authentication with respect to an authentication server througha network, and only a communication device that has succeeded in theauthentication is allowed to communicate through a network, therebytightening the security. Further, according to the IEEE802.1X standard,even in a case where a communication device has been authenticated andconnected to a network, the communication device is required to getre-authentication for each predetermined period of time. Accordingly, inthe case of a printing device provided with the above-describedcommunication device, a request for a re-authentication process willcome in while a print process is being conducted, and a process requiredfor re-authentication needs to be conducted concurrently with the printprocess so as to maintain the connection to the network in such a case.

Japanese Laid-open Patent Publication No. 2011-82922 (Patent Document 1)is an example of the related art.

SUMMARY Problems to be Solved by the Invention

There are cases, however, in which the throughput of reception of printdata is temporarily deteriorated because transmission and reception ofdata for authentication and reception of print data are conductedconcurrently on the same network route if an authentication process isconducted in the middle of receiving an enormous quantity of print data.Especially, if a print process is conducted by receiving print data foreach page or for each line and sequentially printing the received printdata in the environment in which a low-speed network line is used or theline is busy, the reception speed of print data is lower than theprocessing speed of printing, and there is fear that the print processis interrupted.

Means Used to Solve the Above-Mentioned Problems

The invention has been made to address the above-describedcircumstances, and the advantage of the invention is to prevent theefficiency of printing from being deteriorated due to execution of anauthentication process during a print process by arranging anauthentication process not to be conducted during a print process.

A printing device of the invention, to be connected to an authenticationdevice that disconnects a connection between a device and a network in acase where authentication of the device connected to the network fails,includes an authentication requesting means that requests theauthentication process with respect to the authentication device, and aprint processing means that conducts a print process. In the printingdevice, in a case where the print processing means conducts the printprocess, the authentication requesting means requests the authenticationprocess before the print processing means starts the print process.

With this configuration, since the authentication process is requestedwith respect to the authentication device before the print processingmeans starts the print process, the authentication process is conductedbefore the print process is conducted. Therefore, the efficiency of theprint process can be prevented from being deteriorated due to executionof the authentication process during the print process.

BRIEF DESCRIPTION OF THE DRAWINGS

Referring now to the attached drawings which form a part of thisoriginal disclosure:

FIG. 1 is a configuration diagram that schematically illustrates aconfiguration of a network system provided with a multi-purpose deviceaccording to an embodiment of the invention;

FIG. 2 is a diagram that explains data stored in a flash memory;

FIG. 3 is a flow chart that shows a flow of a first process in a casewhere the multi-purpose device receives print data;

FIG. 4 is a flow chart that shows a flow of printing;

FIG. 5 is a flow chart that shows a flow of a second process in a casewhere the multi-purpose device receives print data; and

FIG. 6 is a flow chart that shows a flow of a third process in a casewhere the multi-purpose device receives print data.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

Hereinafter, an embodiment of the invention will be described withreference to the drawings.

Embodiment

FIG. 1 is a configuration diagram that schematically illustrates aconfiguration of a network system 10 provided with a multi-purposedevice 20 as the embodiment of the printing device of the invention. Asshown in the drawing, the network system 10 has a LAN 12, themulti-purpose device 20, a user PC 50, and an authentication server 70.The LAN 12 has an authentication switch 60. The authentication server 70is connected to the LAN 12. The multi-purpose device 20 and the user PC50 are connected to the LAN 12 through the authentication switch 60.

The LAN 12 has the authentication switch 60 as the authenticationdevice, and is configured as a network in accordance with the IEEE802.1Xstandard. The authentication switch 60 is configured as a switching hubwith an authentication function. The authentication switch 60 has acommunication port control section 61, a communication deviceauthentication section 62, a storing section 63, and a communicationinterface (I/F) 64. The communication port control section 61 controls acommunication port which is not shown in the drawing. The communicationdevice authentication section 62 conducts authentication of devices suchas the multi-purpose device 20, the user PC 50, and the like, which areconnected to the communication port. The storing section 63 storesvarious kinds of programs or various kinds of data. The communicationinterface (I/F) 64 is a device that communicates with the multi-purposedevice 20, and the like. The authentication switch 60 is connected tothe LAN 12, the multi-purpose device 20, and the user PC 50 through thecommunication I/F 64. The communication port control section 61 detectsinformation transmitted from devices connected to the communication portsuch as the multi-purpose device 20, the user PC 50, and the like, so asto cause the communication device authentication section 62 to start anauthentication process. Further, the communication port control section61 allows the device that has succeeded in the authentication process toconnect to the LAN 12, and disconnects a connection to the LAN 12 withrespect to the device that has failed in the authentication process.

The communication device authentication section 62 conducts mediation ofan authentication process between the authentication server 70 and thedevices (also referred to as client) connected to the authenticationswitch 60 such as the multi-purpose device 20 or the user PC 50. Morespecifically, the communication device authentication section 62converts a MAC frame, received from the client side such as themulti-purpose device 20 or the user PC 50 in the authentication process,into a RADIUS frame, and transmits it to the authentication server 70.The communication device authentication section 62 converts a RADIUSframe, received from the authentication server 70, into a MAC frame, andtransmits it to the client. Further, the communication deviceauthentication section 62 periodically conducts re-authentication to theclient, that has succeeded in the authentication process and has beenallowed to connect, in accordance with a predetermined period of time“T” (for example, 60 minutes). The communication device authenticationsection 62 also conducts re-authentication of the client based on are-authentication request (authentication request signal) transmittedfrom the client that has been allowed to connect.

In the present embodiment, when re-authentication is conducted inresponse to the re-authentication request from the client, a timer formeasuring (counting) time is reset, and counting the predeterminedperiod of time “T” is started again. Further, in the present embodiment,the authentication process conducted through the authentication switch60 is conducted by an EAP-TLS method as an authentication protocol (EAP)of IEEE802.1X. The EAP-TLS method is a method for conductingauthentication by using an electronic certificate, in whichauthentication is conducted by transmitting and receiving data aplurality of times with a predetermined procedure. The storing section63 stores information used for an authentication process such asauthentication server information 66 that is information regarding theauthentication server 70. Incidentally, the present embodiment usesIEEE802.1X as the standard of the network. However, the presentembodiment is not limited to this as long as it is a standard forperiodically conducting re-authentication to a connected device.

The multi-purpose device 20 is a device that has a scanner function, aprinter function, and a copy function. The multi-purpose device 20 isconnected to a network such as the LAN 12 or the like by conducting anauthentication process in accordance with the IEEE802.1X standard. Then,the multi-purpose device 20 can acquire print data or data of anelectronic certificate and the like from another device, connected tothe network (for example, the user PC 50), by communication through thenetwork, or can transmit scanned image data to another device throughthe network. The multi-purpose device 20 is connected to theauthentication switch 60 through a communication I/F 26, for example, bya LAN cable. The multi-purpose device 20 has a printing mechanism 21, areading mechanism 22, an operating panel 23, and a controller 30. Theprinting mechanism 21 generates an image based on print data onto amedium such as paper or the like. The reading mechanism 22 scans animage or the like on the medium to make image data. The operating panel23 displays various kinds of information for a user, and various kindsof instructions are input to the operation panel 23 by a user. Thecontroller 30 controls the entire device. The printing mechanism 21 isan ink-jet type mechanism (print means) that generates an image based onprint data onto a medium by applying a pressure to ink of each color andejecting this ink onto the medium. In the present embodiment, print datais transmitted from the user PC 50 through the LAN 12 for each pluralityof lines. Regarding a mechanism for applying a pressure to ink,deformation of a piezoelectric element can be used, or generation of airbubbles by heat of a heater can be used.

The printing method is not limited to an ink-jet method, and anelectrophotographic method such as a laser printer can be possible. Insuch a case, print data is transmitted from the user PC 50 through theLAN 12 for each page. The reading mechanism 22 is configured as ascanner mechanism that reads a document by causing a well-known colorimage sensor to scan, in which reflected light after emitting lighttoward a document placed on a glass board is decomposed to each color tomake read data. The operating panel 23 has a displaying section that isconfigured as a liquid crystal display for displaying an image, and anoperating section in which an inputting section is provided so as toallow a user to conduct various kinds of inputting. The displayingsection outputs various kinds of information to a user, and instructionsof a user are input by the operating section.

The controller 30 of the multi-purpose device 20 serves as the printprocessing section, and is configured as a microprocessor centered on aCPU 31. The controller 30 of the multi-purpose device 20 includes a RAM32 that temporarily stores data or saves data, and a flash memory 33that can store and rewrite various kinds of processing programs orvarious kinds of data. The flash memory 33 has a communication settinginformation area 40, a client certificate area 41, and a CA certificatearea 42. The communication setting information area 40 storescommunication setting information for communicating with another devicethrough the communication I/F 26. The client certificate area 41 storesan electronic certificate (also referred to as a client certificate) forcertifying the multi-purpose device 20 itself. The CA certificate area42 stores a CA certificate (a route CA certificate and an intermediateCA certificate). FIG. 2 is a diagram that explains data stored in theflash memory 33. As shown in the drawing, the communication settinginformation area 40 stores various kinds of setting information neededfor communication such as IEEE802.1X setting information for conductcommunication in accordance with IEEE802.1X. Examples of the IEEE802.1Xsetting information include information that shows whether IEEE802.1X iscurrently enabled or disabled, information that designates anauthentication method or a client certificate used for theauthentication, and information that designates a user ID, a server ID,and a CA certificate corresponding to the server ID.

The client certificate area 41 stores an electronic certificate forcertifying the multi-purpose device 20 itself such as a clientcertificate “A”. The client certificate “A” has a basic area, anextended area, and a signature of the certificate authority. The basicarea includes applicant information (also referred to as actorinformation) that is information on the multi-purpose device 20, itsuser, and the like, issuer information that is information on thecertificate authority who issued the client certificate “A”, expirationdata, and the like. The applicant information includes a country name, acompany name, or a department name of the multi-purpose device 20 andits user, or information on the IP address of the multi-purpose device20, and the like, for example. If information on the applicant isregistered in advance in CSR (certificate signature request), which isnot shown in the drawing, transmitted to the certificate authority so asto request issuance of a client certificate, the information will bereflected in the applicant information of the issued client certificate.Therefore, a user or an administrator of the multi-purpose device 20 canarbitrarily determine what kind of information should be included in theapplicant information at the time of making the CSR.

The client certificate stored in the client certificate area 41corresponds to use setting information including information on theclient certificate such as a purpose of the client certificate and thelike. For example, the client certificate “A” corresponds to use settinginformation including information that the purpose of the clientcertificate “A” is IEEE802.1X. The CA certificate area 42 stores a CAcertificate such as route CA certificates “A” and “B”, or intermediateCA certificates “A” and “B”. The CA certificate stored in the CAcertificate area 42 is used for verifying credibility of the clientcertificate stored in the client certificate area 41, a servercertificate acquired in the authentication process, or the like. Thereare cases in which a certificate chain is constructed in the clientcertificate stored in the client certificate area 41. In such cases, aseries of CA certificate from the client certificate to the route CAcertificate correspond to the client certificate.

Back to FIG. 1, the controller 30 inputs various kinds of operationsignals or various kinds of detection signals from the printingmechanism 21 and the reading mechanism 22, inputs operation signals thatare generated in response to operation of the operating section of theoperating panel 23, and inputs various kinds of data, transmitted fromanother device, through the communication I/F 26. Also, the controller30 outputs instructions of printing an image to the printing mechanism21, outputs instructions of reading a document to the reading mechanism22, displays display instructions or an image to be printed on thedisplay section of the operating panel 23, and outputs various kinds ofdata, to be transmitted to another device, to the communication I/F 26.

The controller 30 has a communication control section 34, anauthentication requesting section 35, and a print control section 36 asfunctional blocks. These sections achieve predetermined functions bycausing hardware including the CPU 31, the RAM 32, or the flash memory33, and software stored in the RAM 32 or the flash memory 33 tocooperate with each other. The communication control section 34 controlscommunication with another device connected through the communicationI/F 26. The communication control section 34 has the IEEE802.1X functionthat is a function as wpa_supplicant to connect to a network such as theLAN 12 by conducting an authentication process with an EAP-TLS method, aPEAP/MSCHAPv2, or the like, in accordance with the IEEE802.1X standard,or a function of transmitting and receiving data through the networkafter the authentication process succeeded. Further, the communicationcontrol section 34 refers to information of the communication settinginformation area 40, the client certificate area 41, and the CAcertificate area 42 as needed when the authentication process isconducted.

The print control section 36 controls the printing mechanism 21. Theprint control section 36 transmits print data to the printing mechanism21, and instructs the printing mechanism 21 to print and generate animage based on the print data onto a medium. Here, in a case where theprint control section 36 instructs the printing mechanism 21 to print,the print control section 36 sends a request for authentication to theauthentication requesting section 35 before starting a print process.Also, the print control section 36 confirms that the authentication hasbeen finished or a notification that authentication is unnecessary hasbeen received, and instructs to start a print process. Also, the printcontrol section 36 estimates time required for printing. In the presentembodiment, as an example of estimation of the required time forprinting, estimation is conducted based on the size of print data.Specifically, in the case of an LPR (line printer protocol) that is aprotocol commonly used for network printing, after a printer job isreceived and a control file for printing is received, the size of a datafile for printing is transmitted. Also, in the multi-purpose device 20,the warm-up time for enabling a start of a print process and the numberof data that can be processed for each unit time are recorded in themain body in advance as the system performance.

When “S” (byte) represents the size of the print data obtained by theLPR, “V” (byte/second) represents the average print processing speedstored in advance as the system performance, and “U” (second) representsthe warm-up time, the time required for printing “Q” from receiving datato finishing a print process can be expressed by the following equation:

Q=S/V+U   (Equation 1)

However, a correct data file size cannot be acquired depending on thesettings of the user side. In such a case, maximum time required for aprint process of one page is set as “Q”. The authentication requestingsection 35 refers to the time required for printing “Q” estimated inthis manner as needed. The authentication requesting section 35 sends anauthentication requesting signal that requests authentication of themulti-purpose device 20 itself to the authentication switch 60 based onthe authentication request sent from the print control section 36(authentication requesting means).

In the present embodiment, the communication control section 34 retainsinformation on lapse time “P” since the authentication switch 60requests re-authentication for the last time, and information on thepredetermined period of time “T” for the authentication request of theauthentication switch 60 in a referable manner. The authenticationrequesting section 35 acquires information retained by the communicationcontrol section 34 or the time required for printing “Q” estimated bythe print control section 36, and determines transmission of theauthentication requesting signal based on the acquired information.Here, the authentication requesting section 35 judges whether or not thetime required for printing “Q” of a next pending print process is longerthan remaining time (T−P) until a next re-authentication process isconducted, that is, whether or not a next re-authentication process willbe conducted by the end of the print process of the print data. As aresult, in a case where it is judged that the time required for printing“Q” is longer as in the following conditional equation and a nextre-authentication process will be conducted by the end of the printprocess of the print data, the authentication requesting signal istransmitted.

Q>(T−P)   (Equation 2)

On the other hand, in a case where Equation 2 is not satisfied, theauthentication requesting signal is not transmitted, and a notificationthat authentication is unnecessary is sent back to the print controlsection 36. As a result, the print control section 36 instructs theprinting mechanism 21 to conduct printing after the print controlsection 36 conducts the print process of the print data.

The authentication requesting signal transmitted to the authenticationswitch 60 is received by the authentication switch 60 through thecommunication I/F 26 of the multi-purpose device 20, and thecommunication device authentication section 62 conductsre-authentication of the multi-purpose device 20 based on the receivedauthentication requesting signal. Then, in a case where there-authentication is finished, a notification that authentication hasbeen finished is sent back to the print control section 36. As a result,the timer for counting in order the authentication switch 60 to conductre-authentication is reset, and the authentication switch 60 does notrequest re-authentication until the predetermined period of time “T”passes after the re-authentication. Accordingly, a re-authenticationprocess can be prevented from being conducted during the print processof the print data. Depending on the type of the authentication switch60, there are cases in which the timer will not be reset. In such cases,the multi-purpose device 20 issues a disconnecting process of thenetwork to the authentication switch 60, and the timer can be reset byconducting an authentication process immediately after that.

The user PC 50 is a well-known general-purpose personal computer inwhich each function is controlled by a predetermined OS. The user PC 50is a device that can transmit and receive data by communication withanother device (for example, the multi-purpose device 20 or theauthentication server 70) connected to a network such as the LAN 12through the network. The user PC 50 is connected to the authenticationswitch 60 through a communication I/F 54, for example, by a LAN cable.The user PC 50 has a communication control section 51 as a functionalblock constructed by a CPU for conducting various kinds of control, aROM for storing various kinds of control programs, a RAM for temporarilystoring data, and the like, and a storing section 53 constructed by anHDD and the like that is a high-capacity memory, as hardware. The userPC 50 also has a display 58 for screen-displaying various kinds ofinformation, and an inputting device 59 for allowing a user to inputvarious kinds of instructions such as a keyboard. Further, a printerdriver is installed in the user PC 50 as a function of controlling aprint process by the multi-purpose device 20. This printer drivergenerates a print job (print data) for printing a designated image bythe multi-purpose device 20 based on a user's instructions.

The communication control section 51 controls communication with anotherdevice connected through the communication I/F 54. For example, thecommunication control section 51 conducts an authentication process ortransmits and receives data after the authentication process succeededby using communication setting information 56 or a client certificate 57stored in the storing section 53. Also, the communication controlsection 51 reads out data stored in the communication settinginformation area 40 or the like so as to be displayed on the display 58,and stores data, input by a user through the inputting device 59, in thecommunication setting information area 40 so as to conduct setting orchanging. Also, the communication control section 51 outputs print datato the multi-purpose device 20, and inputs image data read out from themulti-purpose device 20. The communication setting information 56 forcommunicating with another device through the communication I/F 54 orthe client certificate 57 for certifying the user PC 50 itself arestored in the storing section 53.

The user PC 50 is directly connected to the multi-purpose device 20 by aLAN cable. It is thus possible to transmit, from the user PC 50 to themulti-purpose device 20, communication setting information such asIEEE802.1X setting information stored in the communication settinginformation area 40 of the multi-purpose device 20 or an electroniccertificate stored in the client certificate area 41 or the CAcertificate area 42, and store it in the flash memory 33.

The authentication server 70 is configured as a RADIUS server. Theauthentication server 70 is a device that receives an authenticationrequest transmitted from the client such as the multi-purpose device 20or the user PC 50 through the authentication switch 60, and makes aresponse with authentication results by conducting an authenticationprocess to the client by an EAP-TLS method in IEEE802.1X. Theauthentication server 70 is connected to the LAN 12 through thecommunication I/F 74. The authentication server 70 has a clientauthentication section 71 for conducting an authentication process, anda storing section 73 for storing various kinds of programs or variouskinds of data. The storing section 73 stores authentication information76 used for an authentication process such as a CA certificate, anintermediate CA certificate, or a client ID, or a server certificate 78for certifying the authentication server 70 itself.

FIG. 3 is a flow chart that shows a flow of a first process in a casewhere the multi-purpose device 20 receives print data. In the firstprocess, an authentication process is conducted before starting a printprocess in a case where print data is received. First, the CPU 31 of themulti-purpose device 20 receives a print starting packet (step S100).Next, the CPU 31 requests a re-authentication process with respect tothe authentication switch 60 (step S102). Next, the CPU 31 judgeswhether the authentication succeeded or not (step S104). In a case wherethe authentication succeeded (Yes in step S104), the CPU 31 conducts aprint process (step S110), and a series of processes are finished. Onthe other hand, in a case where the authentication failed (No in stepS104), the CPU 31 displays authentication error information on theoperating panel 23 (step S106), and a series of processes are finishedwithout conducting a print process. FIG. 4 is a flow chart that showsthe details of the print process of step S110. When the print process isstarted, the CPU receives print data (step S112). Next, the CPU 31judges whether all data for a print unit has been received or not (stepS114). In a case where all data has not been received (No in step S114),the process returns to step S112. In the present embodiment, the printunit is per line or page. On the other hand, in a case where all datafor a print unit has been received (Yes in step S114), the CPU 31instructs the printing mechanism 21 to conduct printing of the receivedprint data (step S116). As a result, the received print data is printedonto a medium.

Subsequently, the CPU 31 judges whether or not there is print data for anext line or page (step S118). In a case where there is print data for anext line or page (Yes in step S118), the process returns to step S112,and print data is received. On the other hand, in a case where there isno print data for a next line or page (No in step S118), the CPU 31judges whether or not there is a job to be printed next (step S120). Ina case where there is a job to be printed next (Yes in step S120), theprocess returns to step S112, and print data for the next job isreceived. On the other hand, in a case where there is no job to beprinted next (No in step S120), a series of processes are finished. FIG.5 is a flow chart that shows a flow of a second process in a case wherethe multi-purpose device 20 receives print data. In the second process,an authentication process is conducted based on time until nextre-authentication in a case where print data is received. First, the CPU31 of the multi-purpose device 20 receives a print starting packet (stepS130). Next, the CPU 31 calculates print required time required for aprint process (step S132) <required time calculation step>, andcalculates time until next re-authentication is conducted by theauthentication switch 60 (step S134) <remaining time calculation step>.Subsequently, the CPU 31 compares the calculated time, and judgeswhether or not printing will be finished by next re-authentication (stepS136) <comparison step>. In a case where it is judged that printing willbe finished by next re-authentication (Yes in step S136), the printprocess (step S110) is conducted, and a series of processes arefinished.

On the other hand, in a case where it is judged that printing will notbe finished by next re-authentication (No in step S136), the CPU 31requests the authentication switch 60 to conduct re-authentication (stepS138) <authentication process requesting step>. Next, the CPU 31 judgeswhether or not it was authenticated (step S140). In a case where it wasauthenticated (Yes in step S140), the CPU 31 conducts the print process(step S110) <print step>, and a series of processes are finished. On theother hand, in a case where it was not authenticated (No in step S140),the CPU 31 displays authentication error information on the operatingpanel 23 (step S142) <display step>, and a series of processes arefinished without conducting a print process.

FIG. 6 is a flow chart that shows a flow of a third process in a casewhere the multi-purpose device 20 receives print data. In the thirdprocess, an authentication process is conducted for each page based ontime until next re-authentication in a case where print data isreceived. It can be configured that a user can select which of the firstprocess, the second process, and the third process will be conducted bythe multi-purpose device 20. First, the CPU 31 of the multi-purposedevice 20 receives a print starting packet (step S150). Next, the CPU 31calculates print required time required for a print process (step S152),and calculates time until next re-authentication is conducted by theauthentication switch 60 (step S154). Subsequently, the CPU 31 judgeswhether or not a print process will be finished by nextre-authentication (step S156). In a case where it is judged that a printprocess will be finished by next re-authentication (Yes in step S156),the process moves on to a step of receiving print data (step S164). Onthe other hand, in a case where it is judged that a print process willnot be finished by next re-authentication (No in step S156), the CPU 31requests the authentication switch 60 to conduct a re-authenticationprocess (step S158).

Next, the CPU 31 judges whether or not it was authenticated (step S160).In a case where it was authenticated (Yes in step S160), the processmoves on to a step of receiving print data (step S164). On the otherhand, in a case where it was not authenticated (No in step S160), theCPU 31 displays authentication error information on the operating panel23 (step S162), and a series of processes are finished withoutconducting a print process. In the step of receiving print data (stepS164), the CPU 31 receives print data. Next, the CPU 31 judges whetherall data for a print unit has been received or not (step S166). In acase where all data has not been received (No in step S166), the processreturns to step S164.

On the other hand, in a case where all data for a print unit has beenreceived (Yes in step S166), the CPU 31 instructs the printing mechanism21 to conduct printing of the received print data (step S168). As aresult, the received print data is printed. Subsequently, the CPU 31judges whether or not there is print data for a next line or page (stepS170). In a case where there is print data for a next line or page (Yesin step S170), the process returns to step S152, and print required timerequired for a print process is calculated. On the other hand, in a casewhere there is no print data for a next line or page (No in step S170),a series of processes are finished.

According to the above-described embodiment, in the first process,re-authentication is conducted always before a print process isconducted. Also, in the second and third processes, if it is assumedthat authentication is conducted during printing based on time until anext periodical authentication process and print required time requiredfor a print process of print data, re-authentication is conducted beforeprinting. Consequently, it is possible to prevent printing from beinginterrupted due to deterioration in the throughput by conducting anauthentication process during a print process. A device for implementingthe above-described technique includes various kinds of embodiments.There are cases in which it is achieved by a single device, and thereare cases in which it is achieved by combining a plurality of devices.

What is claimed is:
 1. A printing device, to be connected to anauthentication device that disconnects a connection between a device anda network in a case where authentication of the device connected to thenetwork fails, comprising: an authentication requesting section thatrequests the authentication process with respect to the authenticationdevice; and a print processing section that conducts a print process,wherein in a case where the print processing section conducts the printprocess, the authentication requesting section requests theauthentication process before the print processing section starts theprint process.
 2. The printing device according to claim 1, wherein in acase where the print processing section conducts the print process, theauthentication requesting section requests the authentication processwith respect to the authentication device before the print processingsection starts the print process when it is judged that theauthentication device will conduct a periodical authentication processbefore the print process is finished after the print process is startedby the print processing section.
 3. The printing device according toclaim 2, wherein the authentication requesting section acquiresremaining time until the periodical authentication process is conductednext and print required time required for conducting the print process,and requests the authentication process when the print required time islonger than the remaining time.
 4. The printing device according toclaim 1, wherein the print processing section starts the print processafter the authentication process by the authentication device isfinished.
 5. The printing device according to claim 1, wherein theauthentication device requests the authentication process to anauthentication server and receives results of the authentication processfrom the authentication server in a case of receiving the authenticationrequest form the printing device, and the printing device disconnects aconnection to a network through the authentication device in a casewhere authentication of the device by the authentication process fails.6. The printing device according to claim 1, wherein the authenticationrequesting section requests the authentication process with respect tothe authentication device in a case where print required time requiredfor a print process is longer than remaining time until theauthentication process conducted periodically is conducted next.
 7. Theprinting device according to claim 6, further comprising: a displaysection that displays information on authentication error in a casewhere it is not authenticated in the authentication process.
 8. Aprinting system, in which an authentication device connected to aprinting device causes an authentication server to conduct anauthentication process for authentication of a device, and a connectionbetween the printing device and a network is disconnected in a casewhere the authentication of a device by the authentication processfails, the printing device comprising: an authentication requestingsection that requests the authentication process with respect to theauthentication device; and a print processing section that conducts aprint process, wherein in a case where the print processing sectionconducts the print process, the authentication requesting sectionrequests the authentication process before the print processing sectionstarts the print process.
 9. A method for controlling a printing deviceto be connected to an authentication device that disconnects aconnection between a device and a network in a case where authenticationof the device connected to the network fails, wherein in a case wherethe print device conducts a print process, an authentication process forauthenticating the printing device is requested to the authenticationdevice before the print process is started.